Illuminating device, image reading apparatus and image forming apparatus

Abstract

An illuminating device ( 210 ) according to an embodiment of the invention included in an image reading apparatus ( 100 ) and an image forming apparatus (D) includes light source portions ( 211 a 1 ), ( 211 b 1 ), ( 211 a 2 ) and ( 211 b 2 ), light-guiding members ( 213 a ) and ( 213 b ) for illuminating an illumination target (G) from an elongated light emitting face (M) that extends in a longitudinal direction (Y), by guiding light from the light source portions, and holding members ( 216 a ) and ( 216 b ) for holding the light-guiding members. The holding members include holding portions ( 2161 a ) and ( 2161 b ) for removably holding the light-guiding members, and tilted portions ( 2162 a ) and ( 2162 b ) that reflect light emitted from the light emitting face (M), the tilted portions extending from a front end on the light emitting face (M) side of the holding portions, obliquely widening with increasing distance from the light-guiding members.

The invention claimed is: 
     
       1. An illuminating device comprising:
 a light-emitting element; 
 a substrate on which the light-emitting element is mounted; and 
 a light-guiding member which guides light from the light-emitting element via a longitudinal end face of the light-guiding member and thereby illuminates an illumination target from a light emitting face that extends in a longitudinal direction of the light-guiding member, 
 wherein the illuminating device further comprises:
 a first radiator member arranged so as to be opposite to a light-emitting element-mounted surface side of the substrate; and 
 a second radiator member arranged in contact with a surface opposite to the light-emitting element-mounted surface of the substrate and the first radiator member, 
 
 wherein the first radiator member is provided with a through hole for passing the light from the light-emitting element to the end face of the light-guiding member. 
 
     
     
       2. The illuminating device according to  claim 1 ,
 wherein the first radiator member, the substrate, and the 
 second radiator member are arranged in this order in the longitudinal direction of the light-guiding member, from a central portion side of the light-guiding member to an end portion side thereof. 
 
     
     
       3. The illuminating device according to  claim 1 , further comprising:
 a light source light-guiding unit including the light-guiding member, the first and second radiator members, and the light-emitting element; and 
 a base to which the light source light-guiding unit is attached, 
 wherein a radiator member serves as an attachment member for attaching the light source light-guiding unit to the base. 
 
     
     
       4. The illuminating device according to  claim 1 ,
 wherein a connector is provided on the light-emitting element-mounted surface of the substrate. 
 
     
     
       5. The illuminating device according to  claim 1 ,
 wherein at least one of the first radiator member and the second radiator member is formed of aluminum. 
 
     
     
       6. The illuminating device according to  claim 1 ,
 wherein the first radiator member is arranged in contact with the longitudinal end face of the light-guiding member. 
 
     
     
       7. The illuminating device according to  claim 1 ,
 wherein the first radiator member and the second radiator member are fixed to each other by a fastening member in such a manner as to hold the substrate therebetween. 
 
     
     
       8. The illuminating device according to  claim 1 ,
 wherein the light-guiding member is held by a holding member made of a metal material. 
 
     
     
       9. The illuminating device according to  claim 1 , further comprising:
 a heat release structure composed of the first radiator member, the substrate, and the second radiator member, on each side of the light-guiding member in a longitudinal direction thereof. 
 
     
     
       10. The illuminating device according to  claim 1 ,
 wherein the first radiator member serves as a reflecting member for reflecting the light from the light-emitting element. 
 
     
     
       11. An image reading apparatus comprising the illuminating device according to  claim 1 . 
     
     
       12. An image forming apparatus comprising the image reading apparatus according to  claim 11 .